首先添加第二个字符串后，无法读取double或int

更新时间：2023-02-06 19:37:21

我们假设你的文件看起来像这样

我在之后添加了一个 inFile.nextLine（） double Unit1Assistant4rate = inFile.nextDouble（）; ，它对我来说可以正常工作。在我添加之前，我得到了你所做的相同的异常。但现在没关系。

  String Unit1 = inFile.nextLine（）; 
 double NumberofAssistantsUnit1 = inFile.nextDouble（）; 
 double Unit1Assistant1hours = inFile.nextDouble（）; 
 double Unit1Assistant1rate = inFile.nextDouble（）; 
 double Unit1Assistant2hours = inFile.nextDouble（）; 
 double Unit1Assistant2rate = inFile.nextDouble（）; 
 double Unit1Assistant3hours = inFile.nextDouble（）; 
 double Unit1Assistant3rate = inFile.nextDouble（）; 
 double Unit1Assistant4hours = inFile.nextDouble（）; 
 double Unit1Assistant4rate = inFile.nextDouble（）; 

 inFile.nextLine（）; 

 String Unit2 = inFile.nextLine（）; 
 double NumberofAssistantsUnit2 = inFile.nextDouble（）; 
 double Unit2Assistant1hours = inFile.nextDouble（）; 
 double Unit2Assistant1rate = inFile.nextDouble（）; 
 double Unit2Assistant2hours = inFile.nextDouble（）; 
 double Unit2Assistant2rate = inFile.nextDouble（）; 
 double Unit2Assistant3hours = inFile.nextDouble（）; 
 double Unit2Assistant3rate = inFile.nextDouble（）; 
 double Unit2Assistant4hours = inFile.nextDouble（）; 
 double Unit2Assistant4rate = inFile.nextDouble（）; 

 System.out.println（This works fine）;

在我添加了 inFile.nextLine（）。该异常指向此行 double NumberofAssistantsUnit2 = inFile.nextDouble（）; 。所以我假设代码的第一部分工作。只是当程序试图读取第二组文本时， String Unit2 = inFile.nextLine（）; 在 nextDouble（）作为字符串。所以下一行将是 Unit2 ，而不是您期待的 double 。当结合 String s和其他值类型的读取时，会发生这种情况。我喜欢逐行阅读并分割，以避免这个问题。

在使用文件OP编辑后编辑

尝试这个代码。这是可运行的为我工作只需替换文件名

  import java.io.FileNotFoundException; 
 import java.io.FileReader; 
 import java.util.Scanner; 

 public class Assignment3 {

 static Scanner console = new Scanner（System.in）; 

 public static void main（String [] args）throws FileNotFoundException {

扫描仪输入= new Scanner（新的FileReader（aptunits.txt））; 

 int unit = 1; 
 while（input.hasNextLine（））{
 String line = input.nextLine（）; 
 System.out.println（line）; 

 double total = 0; 

 int助手= input.nextInt（）; 
 System.out.println（助理人数+助理）; 
 System.out.println（小时费率）; 
 System.out.println（------------）; （int i = 0; i< assistantants; i ++）{
 int hours = input.nextInt（）; 

 System.out.print（hours +）; 
 double rate = input.nextDouble（）; 
 System.out.println（rate）; 
总+ =（小时*率）; 
} 
 System.out.println（Unit of Unit+ unit +is+ total）; 
 System.out.println（）; 
 unit ++; 

 if（input.hasNextLine（））{
 input.nextLine（）; 
 input.next（）; 
} 

} 
} 
}

so I'm very very new to java and I'm having a slight problem. I'm adding various doubles and integers and trying to read data from a file, but when I try read data from the file after the second string, I am given an error. Anything before the second string is fine.

Here's my code;

import java.util.*;
import java.io.*;

public class Assignment3 {

static Scanner console = new Scanner (System.in);

public static void main(String[] args) throws FileNotFoundException {


Scanner inFile = new Scanner(new FileReader("AssistantHoursAndRates.txt"));

    String Unit1 = inFile.nextLine();
    double NumberofAssistantsUnit1 = inFile.nextDouble();
    double Unit1Assistant1hours = inFile.nextDouble();
    double Unit1Assistant1rate = inFile.nextDouble();
    double Unit1Assistant2hours = inFile.nextDouble();
    double Unit1Assistant2rate = inFile.nextDouble();
    double Unit1Assistant3hours = inFile.nextDouble();
    double Unit1Assistant3rate = inFile.nextDouble();
    double Unit1Assistant4hours = inFile.nextDouble();
    double Unit1Assistant4rate = inFile.nextDouble();

    String Unit2 = inFile.nextLine();
    double NumberofAssistantsUnit2 = inFile.nextDouble();

I am given this error when I try read anything after the second string;

Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextDouble(Unknown Source)
at Assignment3.main(Assignment3.java:28)

I am unsure at to why I am receiving this error, any help would be appreciated, thanks.

Here is the input file for those who were asking;

Unit One
4
32 8
38 6
38 6
16 7

Unit Two
0

Unit Three
2
36 7
36 7

Unit Four
6
32 6.5
32 6.5
36 6.5
36 6.5
38 6.5
38 6.5

Unit Five
4
32 6.5
32 8
32 7
32 8

Unit Six
5
38 7
30 6.5
24 8
24 8
24 8

Unit Seven
0

Unit Eight
1
40 12

Unit Nine
5
24 8
24 6.5
30 6.5
24 7
32 7

Let's say you file looks like this

Unit1
10.00
40.00
15.00
40.00
15.00
40.00
15.00
40.00
15.00
Unit1
10.00
40.00
15.00
40.00
15.00
40.00
15.00
40.00
15.00

I just added an inFile.nextLine() after double Unit1Assistant4rate = inFile.nextDouble(); and it works fine for me. Before I added it, I got the same Exception you did. But now it's fine.

    String Unit1 = inFile.nextLine();
    double NumberofAssistantsUnit1 = inFile.nextDouble();
    double Unit1Assistant1hours = inFile.nextDouble();
    double Unit1Assistant1rate = inFile.nextDouble();
    double Unit1Assistant2hours = inFile.nextDouble();
    double Unit1Assistant2rate = inFile.nextDouble();
    double Unit1Assistant3hours = inFile.nextDouble();
    double Unit1Assistant3rate = inFile.nextDouble();
    double Unit1Assistant4hours = inFile.nextDouble();
    double Unit1Assistant4rate = inFile.nextDouble();

    inFile.nextLine();

    String Unit2 = inFile.nextLine();
    double NumberofAssistantsUnit2 = inFile.nextDouble();
    double Unit2Assistant1hours = inFile.nextDouble();
    double Unit2Assistant1rate = inFile.nextDouble();
    double Unit2Assistant2hours = inFile.nextDouble();
    double Unit2Assistant2rate = inFile.nextDouble();
    double Unit2Assistant3hours = inFile.nextDouble();
    double Unit2Assistant3rate = inFile.nextDouble();
    double Unit2Assistant4hours = inFile.nextDouble();
    double Unit2Assistant4rate = inFile.nextDouble();

    System.out.println("This works fine");

Before I added the inFile.nextLine(). The exception pointed to this line double NumberofAssistantsUnit2 = inFile.nextDouble();. So I assumed the first part of code worked. It's just when the program tried to read the the second set of text, the String Unit2 = inFile.nextLine(); ate up the empty space after the nextDouble() as the String. So the next line would be Unit2 instead of the double you were expecting. This happens when combining the reading of Strings and other value types. I prefer to read line by line and split, to avoid this problem.

Edit after OP edit with file

Try this code out. It's Runnable. Works for me. Just replace the file name

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Scanner;

public class Assignment3 {

    static Scanner console = new Scanner(System.in);

    public static void main(String[] args) throws FileNotFoundException {

        Scanner input = new Scanner(new FileReader("aptunits.txt"));

        int unit = 1;
        while (input.hasNextLine()) {
            String line = input.nextLine();
            System.out.println(line);

            double total = 0;

            int assistants = input.nextInt();
            System.out.println("Number of Assistants " + assistants);
            System.out.println("Hours  Rate");
            System.out.println("------------");
            for (int i = 0; i < assistants; i++) {
                int hours = input.nextInt();
                System.out.print(hours + "     ");
                double rate = input.nextDouble();
                System.out.println(rate);               
                total += (hours * rate);
            }
            System.out.println("Total cost of Unit " + unit + " is " + total);
            System.out.println();
            unit++;

            if (input.hasNextLine()) {
                input.nextLine();
                input.next();
            }

        } 
    }
}

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首先添加第二个字符串后，无法读取double或int

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